Ethereum's Fusaka Upgrade Doubles Data Capacity, Paving Way for $1T L2 Market

Ethereum developers have officially set December 3, 2025, as the activation date for the Fusaka upgrade, marking a critical step in the blockchain’s scaling strategy. The upgrade will follow a phased rollout, beginning with three public testnet deployments in October 2025 across Holesky, Sepolia, and Hoodi. If these tests proceed smoothly, the mainnet launch will proceed as planned. The Fusaka upgrade is designed to enhance Ethereum’s data availability and scalability, particularly for layer-2 (L2) rollups, by implementing a series of technical improvements and incremental blob capacity expansionsETH News: Fusaka Coming in December - CoinDesk^[1].

A key feature of Fusaka is the introduction of Blob Parameter Only (BPO) forks to incrementally increase blob limits. Initially, the upgrade will maintain the current blob target/max of 6/9. However, a first BPO fork on December 17, 2025, will raise the limit to 10/15, followed by a second BPO fork on January 7, 2026, pushing the capacity to 14/21. These adjustments aim to double Ethereum’s blob throughput without requiring client-side software updates, ensuring a smoother transition for node operatorsEthereum Fusaka Upgrade Set for December 3 Mainnet Launch, …^[2]. The phased approach allows developers to monitor performance and validate scalability gains before full implementation.

The Fusaka upgrade also includes the activation of PeerDAS (Peer Data Availability Sampling), a mechanism that reduces the data storage and bandwidth requirements for nodes. By enabling nodes to verify data availability through sampling rather than storing entire blobs, PeerDAS enhances network efficiency and supports higher L2 transaction throughput. This innovation is critical for Ethereum’s long-term goal of achieving 12,000 transactions per second while maintaining decentralization and securityEthereum Fusaka hardfork set for December rollout: what does it …^[3].

In addition to blob scalability, Fusaka addresses gas limit constraints and network resilience. The upgrade increases Ethereum’s block gas limit from 45 million to 60 million, with plans to further expand it to 150 million in future phases. This adjustment, paired with a transaction gas limit cap (EIP-7825), mitigates denial-of-service risks and ensures predictable transaction costs. Other improvements include updated MODEXP precompile pricing and RLP block size limits, which optimize computational efficiency and reduce propagation delaysFulu-Osaka (Fusaka) | ethereum.org^[4].

The strategic timing of Fusaka aligns with Ethereum’s broader roadmap to strengthen base layer capabilities amid growing L2 adoption. Over 93% of Ethereum transactions now occur on L2 networks, yet these chains account for only 13.69% of the ecosystem’s economic value. By reducing blob fees and improving data availability, Fusaka aims to bridge this gap, fostering a more cohesive and scalable infrastructure. Analysts note that the upgrade could catalyze further institutional interest in Ethereum, with forecasts suggesting L2 networks may reach a $1 trillion market capitalization within six yearsEthereum plans the Fusaka update for December 3 - Cryptopolitan^[5].

Developers emphasized the importance of rigorous testing, with a $2 million bounty allocated for security audits of the Fusaka codebase. Node operators must complete software updates by November 3 to ensure compatibility with the mainnet launch. The staggered testnet schedule and automated BPO forks reflect Ethereum’s commitment to minimizing disruptions while prioritizing security and decentralizationEthereum Developer Call Confirms Testnet Schedule - Christine D. Kim^[6].